12-17-2017, 08:52 PM
Just to build on what Hangman has already mentioned, dead silence usually means something has died. 
You either have a dead tube, or an open resistor (probably a plate resistor, or a shorted resistor (particularly one that goes to ground). The thing is, looking at the schematic, there are no fewer than 3 preamp tubes in channel 1, so it is going to take some debugging. The first question is: do all the tubes light up? Fixing a dead tube is by far the easiest thing to do. 
You either have a dead tube, or an open resistor (probably a plate resistor, or a shorted resistor (particularly one that goes to ground). The thing is, looking at the schematic, there are no fewer than 3 preamp tubes in channel 1, so it is going to take some debugging. The first question is: do all the tubes light up? Fixing a dead tube is by far the easiest thing to do.